1. Technical Field
This invention relates generally to electronic copiers, and more particularly to such copiers capable of processing an image signal to adjust magnification to fit a selected copy sheet size, to automatically select a copy sheet size to fit an original document size, and to change the magnification of a portion of an original document.
2. Background Art
It will be appreciated that it may be desirable to be able to alter the effective size of the scanned image to print either an enlarged or reduced version of the image. Image magnification, either reduction or enlargement, may be accomplished in several ways. In DuVall U.S. Pat. No. 4,532,602, a sequence of digital scan values are sampled at frequencies greater or less than the frequency at which the values are produced to provide a sequence of output scan values differing in number from the sequence of input scan values. The size of the image is altered by the ratio of frequencies. In Nagashima U.S. Pat. No. 4,679,096, a read clock generator and a write clock generator vary the frequency of reading data from and writing data to a memory in accordance with a magnification factor.
In many prior art copiers, the magnification factor is automatically selected to match the image size to the size of the copy sheet upon which it is to be reproduced. This feature is known as "auto scaling." Another feature also found on prior art copiers is referred to as "auto paper select," wherein the copy sheet is automatically chosen from a variety of supply sizes to most closely match the size of the original document. To effect auto scaling, both the size of the original document and the size of the copy sheet must be determined before a magnification factor is selected. To effect auto paper select, the size of the original document and of the available copy sheets must be known before a copy sheet size can be selected.
Determining the size of the copy sheet is generally not a problem, and may be accomplished by means of sensors and/or cassette coding. Determining of the size of the original document may be by means of a manual setting by the operator, but this requires an additional operation during machine set-up, and is therefore less desirable than so called "document recognition" techniques, wherein the original document is pre-scanned to gather sufficient data regarding the size and position of an original document on the scanner platen. During a subsequent scan, the image signal is processed according to the size of the original document determined using the data collected during the first scan.
A copier's life is in part limited by the physical number of times the image is scanned, and the inconvenience of the operators is measured in part by the time duration they must wait to remove the original after pressing the start button. A copier which requires only a single scan to determine the size of the original, to determine the magnification factor, and to read the image data would be very preferable to a copier which requires two or more scans for the same functions.
Copiers are also known wherein designated portions, called windows, of the original image are scaled (enlarged or reduced) according to the operator's request. The designation of the window boundaries may be accomplished such as for example by means of a digitalization tablet. After the boundaries are selected, the document is scanned a first time to collect image data of the portion of the original image which lies outside the window boundaries and to process that portion. The document is scanned a second time to capture the portion of the original image which lies inside the window boundaries, effect magnification thereon, and record the magnified image in a overlaid manner with the first portion. Again, the copier's life and the convenience of the operators are negatively impacted by the need to double scan the original.
3. Disclosure of Invention
It is an object of the present invention to provide a copier with the capability to determine the size of the original document, or a designated portion thereof, for purposes of auto scaling, auto paper select, and/or window scaling; to set image magnification parameters; and to process the image signal according to the set parameters in but a single scan of the original document.
In accordance with a feature of the present invention, an electronic copier includes means for forming an image on a copy sheet based on a supplied series of electrical data signals, document recognition means for determining the size of an original document from a series of electrical data signals, memory means for storing a series of electrical data signals representative of the image content of a document and for applying the stored electrical signals to the image forming means, means responsive to the document recognition means for matching the size of a copy sheet and the size of the image formed by the image forming means, and scanning means for generating during a single scan of a document a series of electrical data signals representative of the size and image content of the documents and for applying the generated signals to the document recognition means and to the memory means.
According to a preferred embodiment of the invention, the means for matching the size of a copy sheet and the size of the formed image includes means for scaling the image data signals applied to the image forming means such that the size of the formed image matches the size of a copy sheet, and means for reading the stored series of data signals from the memory means and for applying them to the scaling means. Means may be provided for signaling the size of a selected copy sheet so that a magnification factor may be calculated based on the size of the original document and the size of the selected copy sheet. All of the aforementioned operations are effected in response to but a single scan of an original document. A supply of different size sheets may be provided along with means for selecting a copy sheet from the supply such that the size of the copy sheet corresponds to the size of the original document. The memory means may be adapted to retain the scanned series of data signals even after an image is formed, whereby the matching means can be adjusted and another image formed.
In accordance with another feature of the present invention, an electronic copier for reproducing an image of an original document onto a copy sheet includes means for designating a portion of an original document for scaling, means for designating the magnification of the designated portion, scaling means for scaling the designated portion of received image data and for merging the scaled data with the data from the portion of the original document not designated, memory means for storing a series of electrical data signals representative of the image content of a document and for applying the stored data to the scaling means, image forming means for forming an image on a copy sheet based on a supplied series of electrical data signals, and scanning means for generating, during a single scan of a document, a series of electrical data signals representative of the image content of the documents, and for applying the generated signals to the memory means. Preferably, the memory means is at least twice the size of the image, whereby the memory means can save the merged image without overwriting the original image.
The invention, and its objects and advantages, will become more apparent in the detailed description of the preferred embodiments presented below.